A variety of polypeptide growth factors, including fibroblast growth factors (hereinafter, referred to as FGFs), are known to be expressed in skin tissue. In both mice and humans, FGFs are encoded by twenty-two distinct genes (Ornitz D M, Itoh N: Fibroblast growth factors, Genome Biol. 2: REVIEWS 3005, 2001). Particularly, FGF-1, FGF-2, FGF-5, FGF-7, FGF-10, FGF-13, and FGF-22 are expressed in skin cells and hair follicular cells and control hair growth and skin regeneration (as reported in the following non-patent documents: du Cros D L: Fibroblast growth factor and epidermal growth factor in hair development, J. Invest. Dermatol. 101: 106S-113S. 1993; du Cros D L, Isaacs K, Moore G P: Distribution of acidic and basic fibroblast growth factors in ovine skin during follicle morphogenesis, J. Cell Sci. 105: 667-674, 1993; Hebert J M, Rosenquist T, Gotz J, Martin G R: FGF5 as a regulator of the hair growth cycle: Evidence from targeted and spontaneous mutations, Cell 78: 1017-1025, 1994; Danilenko D M, Ring B D, Yanagihara D, Benson W, Wiemann B, Starnes C O, Pierce G F: Keratinocyte growth factor is an important endogenous mediator of hair follicle growth, development, and differentiation, American J. Pathol. 147: 145-154, 1995; Marchese C, Chedid M, Dirsch O R, et al: Modulation of keratinocyte growth factor and its receptor in reepithelializing human skin, J. Exp. Med. 182: 1369-1376, 1995; Guo L, Degenstein L, Fuchs E: Keratinocyte growth factor is required for hair development but not for wound healing, Genes Dev. 10: 165-175, 1996; Rosenquist T A, Martin G R: Fibroblast growth factor signaling in the hair growth cycle: Expression of the fibroblast growth factor receptor and ligand genes in the murine hair follicle, Developmental Dynamics 205: 379-386, 1996; Petho-Schramm A, Muller H J, Paus R: FGF5 and the murine hair cycle. Arch. Dermatol. Res. 288: 264-266, 1996; Mitsui S, Ohuchi A, Hotta M, Tsuboi R, Ogawa H: Genes for a range of growth factors and cyclin-dependent kinase inhibitors are expressed by isolated human hair follicles, Br. J. Dermatol. 137: 693-698, 1997; Ortega S, Ittmann M, Tsang S H, Ehrlich M, Basilico C: Neuronal defects and delayed wound healing in mice lacking fibroblast growth factor-2, Proc. Natl. Acad. Sci. U.S.A. 95: 5672-5677, 1998; Suzuki S, Kato T, Takimoto H, et al: Localization of rat FGF-5 protein in skin macrophage-like cells and FGF-5S protein in hair follicle: Possible involvement of two Fgf-5 gene products in hair growth cycle regulation, J. Invest. Dermatol. 111: 963-972, 1998; Suzuki S, Ota Y, Ozawa K, Imamura T: Dual-mode regulation of hair growth cycle by two Fgf-5 gene products, J. Invest. Dermatol. 114: 456-463, 2000; Nakatake Y, Hoshikawa M, Asaki T, Kassai Y, Itoh N: Identification of a novel fibroblast growth factor, FGF-22, preferentially expressed in the inner root sheath of the hair follicle, Biochem. Biophys. Acta. 1517: 460-463, 2001; Stenn K S, Paus R: Controls of hair follicle cycling, Physiol. Rev. 81: 449-494, 2001; Beyer T A, Werner S, Dickson C, Grose R: Fibroblast growth factor 22 and its potential role during skin development and repair, Exp. Cell Res. 287: 228-236, 2003; and Kawano M, Suzuki S, Suzuki M, Oki J, Imamura T: Bulge- and basal layer-specific expression of fibroblast growth factor 13 (FHF-2) in mouse skin, J. Invest. Dermatol. 122: 1084-1090, 2004).
Furthermore, JP Patent Publication (Kokai) No. 4-224522 A (1992) discloses a method for promoting hair growth and a method for treating baldness through the use of FGF-5. However, as disclosed in Suzuki S, Ota Y, Ozawa K, Imamura T: Dual-mode regulation of hair growth cycle by two Fgf-5 gene products, J. Invest. Dermatol. 114: 456-463, 2000, FGF-5 gene products are known to have a function of inducing catagen with regard to hair follicular cells. Hence, it is unrealistic to promote hair growth or treat baldness through the use of FGF-5 as disclosed in JP Patent Publication (Kokai) No. 4-224522 A (1992). In addition, detailed examination of the description of such patent document has revealed that such document fails to demonstrate that FGF-5 exerts the effect of promoting hair growth.
Documents including the above non-patent documents suggest the important role of FGFs in skin cell growth and differentiation. However, how FGF family members are involved in the effect of promoting hair follicle growth and the effects of promoting hair growth and hair regrowth following the thus promoted hair follicle growth remains unknown.